Question

I have jslint complaining me to use || operator for below code,

query = ['browser' + (ieVersion ? ieVersion : 'UNKNOWN')]

I tried using || operator but that ends up in wrong result,

query = ['browser' + ieVersion || 'UNKNOWN'] 
// => ['browserundefined']

Answer 1

Operator precedence is wrong, try this:

query = ['browser' + (ieVersion || 'UNKNOWN')]

without extra parentheses + operator is stronger and JavaScript engine evaluates it as:

query = [('browser' + ieVersion) || 'UNKNOWN']

Notice that 'browser' + ieVersion is never falsy so you’ll never see 'UNKNOWN'.